So I talked to Todd of Gardens Unlimited last week about propagation and he said now was the time to take cuttings. He advised taking them where the new growth from last year met the lignified wood. Fast draining soil and keeping them moist but not damp was also recommended.
Since I've heard of success taking larger cutting of shimpaku, as an experiment I also took some 2 and 3 year growth and planted them in the grow medium. This polystyrene container blew into my back yard during a storm about a month ago. I'm glad to have been able to put it to good use.
My inorganic mix in equal parts with garden soil
Different size cuttings soaking in rooting hormone
Cuttings with lower foliage removed
Larger Cuttings were scraped at the base before dipped in rooting hormone
Tray is in place under my bench where it will be clear of winds and receive partial afternoon light for 4-6 weeks.
I'm watering these by misting them heavily so as not to disturb the soil and tear any new roots that may form. If any of these don't turn brown in the next 2 months, I'll feel good about the rootage. They will be put into separate containers in a year.
I hope to be taking some additional air layers from the mother plant this weekend. After this year I'll be more discriminate about cutting this juniper back. The interior is already much more open to sunlight and air since I received it and new foliage is growing closer to the trunk, where I need it.